Questioned about the personal battles she may have faced, he explained: "This is really one of the great tragedies of my professional life that I have watched happen, is that when we started working, Caroline was an innocent, happy young woman with an immense talent."

"By the end of two seasons she was a celebrity and it was only too obvious that she found it very, very difficult to deal with being a celebrity."

Caroline, who had been a smoker, fought depression and drink problems over the years.

Mr Kessler said the much-loved comedy writer and actress had an "enormous natural intellect but not a great deal in the way of formal education".

"There wasn't a great deal she had to fall back on to act as a buffer against that intrusive world of media attention."

He continued: "What she therefore tended to rely on was people who she thought she could trust. And the thing is as you gain celebrity, more and more people present themselves to you as 'I am the person you can trust', and it becomes extremely confusing for an innocent person."

Caroline became a national treasure in the 1990s when she played the mischievous, twinkly-eyed, blue-rinse chat show host Mrs Merton.